A one day Urban Heat Island (UHI) field campaign was conducted in April 2008 in Phoenix, Arizona. Several concurrent measurements of surface temperature were obtained at key locations along an east-west transect across central Phoenix throughout a 24-hour period beginning at 0600 LST. Surface temperatures were obtained every two hours from both hand-held infrared thermography and mobile infrared thermometer (IRT) measurements in order to capture a complete diurnal pattern of temperature over respective land uses in central Phoenix, with different densities, surface, and vegetative properties. Infrared thermography was both helicopter and ground based, while automobile-mounted IRT measurements were obtained across central Phoenix along a mobile route approximately 16 km in length from east to west. A unique approach was utilized to collect thermographic images of built elements in downtown Phoenix, with transportation between image sites via a “pedal cab,” a type of bicycle taxi, and is discussed in more detail in a companion paper by Di Sabitino et al. The micrometeorological three dimensional simulation model Envi-Met was then compared to field observations, focusing specifically on surface and ambient temperatures. Simulation results are in good agreement with mobile observations for ambient temperatures at the 2200 time, as well as surface temperatures along roadways. Experimental and model results will aid planners and others looking for ways to mitigate heat within the city.